It is generally recognized that chewing gum that is dropped in indoor or outdoor environments gives rise to considerable nuisances and inconveniences due to the fact that the dropped gum sticks firmly to e.g. street and pavement surfaces and to shoes and clothes of people being present or moving in the environments. Adding substantially to such nuisances and inconveniences is the fact that currently available chewing gum products are based on the use of elastomeric and resinous polymers of natural or synthetic origin that are substantially non-degradable in the environment.
City authorities and others being responsible for cleanliness of indoor and outdoor environments therefore have to exercise considerable efforts to remove dropped chewing gum, such efforts, however, being both costly and without satisfactory results.
Attempts have been made to reduce the nuisances associated with the widespread use of chewing gum, e.g. by improving cleaning methods to make them more effective with regard to removal of dropped chewing gum remnants or by incorporating anti-sticking agents into chewing gum formulations. However, none of these precautions, which follows mainly two paths, namely either improving the methods of cleaning the chewing gum from a surface or either preparing a chewing gum having non-tack properties, have contributed significantly to solving the pollution problem.
A cleaning agent and a method related to the use of this agent according to the first path are disclosed in US patent application no. 2005/0032670. According to this document and other related methods, a change of consistence of the polluting chewing gum is obtained by means of e.g. steam supplied with chemical reactive agents. A problem related to these post-processing techniques is generally that chewing gum residues are typically accepted.
Several attempt have been made following the second path, namely basically that of avoiding the sticking of chewing gum lump to surfaces. The past two decades have seen an increasing amount of interest paid to synthetic polyesters for a variety of applications ranging from biomedical devices to gum bases. Many of these polymers are readily hydrolyzed to their monomeric hydroxy-acids, which are easily removed by metabolic pathways. Biodegradable polymers are e.g. anticipated as alternatives to traditional non- or low-degradable plastics such as poly(styrene), poly(isobutylene), SBR, and poly(methyl-methacrylate).
Thus, it has recently been disclosed, e.g. in U.S. Pat. No. 5,672,367, that chewing gum may be made from certain synthetic polymers having in their polymer chains chemically unstable bonds that can be broken under the influence of light or hydrolytically into water-soluble and non-toxic components. The document discloses that the nature of the applied polymers results in a reduced adhesion to surfaces.
The same approach in a slightly other direction has been made in U.S. Pat. No. 6,818,236 where a styrene-butadiene rubber is applied in chewing gum and where the disclosed rubber degrades and becomes brittle upon exposure to ultraviolet light (such as sunlight), ozone, heat, and other environmental chemicals.
A problem generally related the second path is that sticking to surfaces of the final chewed chewing gum lumps is hard to avoid without compromising the textural properties of the chewing gum during use.
A problem is however that the expected non-tack properties of so-called biodegradable chewing gum may be present under some conditions for some types of chewing gum, but that the general approach that biodegradable chewing gum has non-tack properties does not apply.